Sensor node, base station, and sensor network system

• US 7,593,752 B2
• Filed: 03/21/2007
• Issued: 09/22/2009
• Est. Priority Date: 01/31/2005
• Status: Active Grant

• Current Assignee: Maxell, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shimura, Takanori, Ara, Koji, Yamashita, Shunzo, Ogata, Yuji
• Primary Examiner(s): Pan; Yuwen
• Assistant Examiner(s): Jain; Ankur
• Application Number:
  US11/723,691
• Publication Number:
  US 20070281758A1
• Time in Patent Office: 916 Days
• Field of Search: 455/574, 455/67.11, 455/561
• US Class Current: 455/561
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G01D 5/00 Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable G01D3/00 takes precedence; specially adapted for apparatus giving results other than momentary value of variable G01D1/00
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 28/14 using intermediate storage
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

This invention achieves lower electric power consumption of a sensor node for carrying out an intermittent operation, in a sensor net system. A time when the sensor node transmits a signal to a base station is estimated. Then, in accordance with the estimation, a table for storing a signal transmitted from the sensor node is installed in a wireless section of the base station. Consequently, a communication time between the sensor node and the base station can be made shorter. Also, a start time of a micro computer is set for RTC inside the sensor node, so the micro computer inside the sensor node can be put in the standby state.

Claims

1. A sensor network system, comprising:

a sensor node comprising a first sensor configured to detect at least one of data of a temperature, acceleration, and illuminance, a first CPU for receiving first data which is at least one of data of a temperature, acceleration, and illuminance detected by the first sensor, a first memory in which software executed by the CPU is installed, a first wireless communication module for transmitting the first data obtained by the first sensor, and a first interface controller; and

a base station comprising a second wireless communication module for receiving the first data transmitted from the first wireless communication module of the sensor node, a second memory for storing the data to be transmitted to the sensor node, a second CPU for controlling the data stored in the second memory to be transmitted to the sensor node, a second sensor configured to detect at least one of data of a temperature, acceleration, and illuminance, and a second interface controller, wherein

the first sensor, the first CPU, the first memory, the first wireless communication module and the first interface controller are connected through a first bus, and

the second sensor, the second CPU, the second memory, the second wireless communication module and the second interface controller are connected through a second bus,

wherein the base station has a third memory which is connected through an interface to the second memory and stores commands to be transmitted to the sensor node,

the second memory stores a portion of the commands stored in the third memory, and

when the base station receives the first data from the sensor node, if the command to be transmitted to the sensor node is stored in the second memory, the command stored in the second memory is transmitted to the sensor node.

2. The sensor network system according to claim 1, wherein

the first sensor and second sensor have the same hardware configuration,

the first CPU and second CPU have the same hardware configuration,

the first memory and second memory have the same hardware configuration,

the first wireless communication module and second wireless communication module have the same hardware configuration, and

the first interface controller and second interface controller have the same hardware configuration.

3. The sensor network system according to claim 1, wherein

the base station further comprises a base station controller which is connected through an interface to the first interface controller and transmits the first data received from the first interface controller through a wired communication to a server.

4. The sensor network system according to claim 1, wherein

if the command to be transmitted to the sensor node is not stored in the second memory, whether or not the command is stored in the third memory is judged.

5. The sensor network system according to claim 4, wherein

if the command is stored in the third memory, the command stored in the third memory is transmitted to the sensor node.

6. The sensor network system according to claim 4, wherein

if the command is not stored in the third memory, an empty signal indicating that there is no command for controlling the sensor node is transmitted to the sensor node instead of the command.

7. The sensor network system according to claim 1, wherein

the second memory further store a second schedule time when the second wireless communication module receives the first data corresponding to each of the commands

and the third memory further store a third schedule time when the second wireless communication module receives the first data corresponding to each of the commands, and

the third schedule time stored in the third memory is later than the second schedule time stored in the second memory.

8. The sensor network system according to claim 7, wherein

each of the commands, which are stored in the second memory and the third memory, is stored in an order of schedule times when the first data are received by the base station, and

the base station, after receiving the first data from the sensor node, rewrites an order of the commands which are stored in the second memory and the third memory.

9. The sensor network system according to claim 1, wherein the commands are not stored in the second memory, and

a flag indicating whether or not the command exists in the third memory is stored in the second memory.